Prevent compiler warnings and potential OLC setting string truncation.

- Prevented compiler warnings when using
’-Wtautological-pointer-compare’ on development system (Darwin)
- Prevented possible string truncation when adding a newline to an OLC
setting string.

src/db.c

@@ -3915,14 +3915,14 @@ void load_config( void )
         else if (!str_cmp(tag, "dflt_dir")) {
           if (CONFIG_DFLT_DIR)
             free(CONFIG_DFLT_DIR);
-          if (line != NULL && *line)
+          if (*line)
             CONFIG_DFLT_DIR = strdup(line);
           else
             CONFIG_DFLT_DIR = strdup(DFLT_DIR);
         } else if (!str_cmp(tag, "dflt_ip")) {
           if (CONFIG_DFLT_IP)
             free(CONFIG_DFLT_IP);
-          if (line != NULL && *line)
+          if (*line)
             CONFIG_DFLT_IP = strdup(line);
           else
             CONFIG_DFLT_IP = NULL;
@@ -3967,7 +3967,7 @@ void load_config( void )
         else if (!str_cmp(tag, "logname")) {
           if (CONFIG_LOGNAME)
             free(CONFIG_LOGNAME);
-          if (line != NULL && *line)
+          if (*line)
             CONFIG_LOGNAME = strdup(line);
           else
             CONFIG_LOGNAME = NULL;